Developing Exciton Tunability in Two-Dimensional Metal-Halide Perovskites*

Inspired by the wide range of optoelectronic tunability that was achieved in the 1980s and 90s for III-V quantum wells systems, we seek to develop the tunability of 2D metal halide perovskite (2D MHP) quantum wells through the large catalog of molecules and atoms that naturally crystalize into the Ruddlesden-Popper A₂BX₄ crystal structure, where A represents an organic cation (barrier layer) and BX₄ represents the metal-halide semiconductor (well layer). We have developed a highly precise and reproducible method for measuring the band gap energy and exciton binding energy of 2D MHPs. We apply this method to a wide range of A₂BX₄ compositions in order to explore the parameter space of band gaps and exciton binding energies that are accessible within this class of quantum wells, and we extrapolate our results to draw implications for exciton tunability in 3D MHPs.